Transport Transports Canada Canada TP 7245E



# AIRWORTHINESS DIRECTIVE

The following airworthiness directive (AD) may be applicable to an aircraft which our records indicate is registered in your na me. ADs are issued pursuant to Canadian Aviation Regulation (CAR) 521 Division X . Pursuant to CAR 605.84 and the further details of CAR Standard 625, Appendix H , the continuing airworthiness of a Canadian registered aircraft is contingent upon compliance with all applicable ADs. Failure to comply with the requirements of an AD may invalidate the flight authorization of the aircraft. Alternative means of compliance shall be applied for in accordance with CAR 605.84 and the above-referenced Standard

. This AD has been issued b y the Continuin g Airworthiness Division ( AARDG ) , National Aircraft Certification Branch, Trans p ort Canada, Ottawa, tele p hone 613 952-4357.

Pursuant to CAR 202.51 the registered owner of a Canadian aircraft shall, within seven days, notify the Minister in writing of any change of his or her name or address. To request a change of address, contact the Civil Aviation Communicat ions Centre (AARC) at Place de Ville, Ottawa, Ontario K1A 0N8 , or 1-800-305-2059 , or www.tc.gc.ca/civilaviation/communications/centre/ address.asp
2 4-0022 ( 01-2005 ) 1/2 No

. CF-2012-02 Issue Date 9 January 2012

Number: CF-2012-02 Subject: Rudder Control System – Seiz ure of the Rudder Feel Trim Unit
Effective: 23 January 2012 Applicability: Bombardier Inc. DHC-8 Aeroplan es Models 400, 401 and 402, Serial Number 4001, 4003 and subsequent, equipped with Rudder Feel Trim Unit Part Number 399500- 1007. Compliance: As indicated below, unless already accomplished. Background: There have been several reported incidents on DHC-8 Series 400 aeroplanes where the movement of the rudder pedals have been impeded. An investigation showed that the Rudder Feel Trim Unit (RFTU) trunnion sha ft was corroded. The root cause of the corrosion was a quality escape where cadmium plating on the trunnion bushing within the RFTU assembly was not removed. Corro sion on the shaft and in the trunnion bushing seized the trunnion and caused difficulties in controlling the rudder movement. This condition, if not corrected, could caus e a rudder control jam or a large and rapid alternating rudder input leading to a stru ctural failure of the vertical fin. This Airworthiness Directive (AD) is issued to replace the affected RFTUs to limit the possibility of binding and replace the affect ed RFTUs with units that have been reworked with conformal bushings to termi nate the lubrication requirements.
Corrective Actions: A. Within 600 hours air time or six months, whichever comes first, from the effective date of this AD, inspect the serial number (S/N) of the RFTU in accordance with the Accomplishment Instructions of Bombar dier Aerospace Service Bulletin (SB) 84-27-57, dated 22 July 2011, or later revi sions approved by the Chief, Continuing Airworthiness, Transport Canada.
1. If the RFTU’s S/N is not in the r ange from 0009 thru 0388 or if the S/N has a suffix “A”, no further action is required. Note: Inspection of the RFTU serial number may be conducted visually on the aeroplane or by checking the maintenance records.
2. If the RFTU’s S/N is in the range from 0009 thru 0388 without a suffix “A”, perform an operational check of the RFTU for any sign of seizure of the trunnion and its bushing in accordance with the Accomplishment Instructions, Paragraph 3.B (Part A) step 3 of the above mentioned SB.No. N ° CF-2012-02 2/2

a. If a seizure of the RFTU trunnion and it s bushing is found, prior to next flight, replace the RFTU in accordance with the Accomplishment Instructions, Paragraph 3.B, Part B of the above mentioned SB.
b. If no seizure of the RFTU trunnion and its bushing is found, lubricate the RFTU in accordance with the Accomp lishment Instructions, Paragraph 3.B, Part C of the above mentioned SB. Repeat the lubrication of the RFTU at intervals not to exceed 600 hours air time until the RFTU is replaced with a unit that has a S/N outside of the affect ed range or a S/N with the suffix “A”.
B. Within 6000 hours air time from the effect ive date of this AD, replace all affected RFTUs with units that have a S/N outside of the affected range or a S/N with the suffix “A” in accordance with the Accomplis hment Instructions, Paragraph 3.B, Part B of the above mentioned SB.
C. As of the effective date of this AD, no person may install a RFTU P/N 399500-1007 with a S/N from 0009 thru 0388 without a suffix “A” on an aeroplane.
Authorization: For the Minister of Transport, Infrastructure and Communities 

### ORIGINAL SIGNED BY Derek Ferguson Chief, Continuing Airworthiness
Contact: Mr. Gordanko Jeremic, Continuing Airworthiness, Ottawa, telephone 613-952-4357, facsimile 613-996-9178 or e-mail CAWWEBFeedback@tc.gc.ca or any Transport Canada Centre.